Scores of natural rockfalls occur in California’s Yosemite Valley every year, often with little or no advance warning, posing hazards to people and infrastructure. In 1980, for example, a fall near Yosemite Falls killed three people and injured 19. Efforts to record and document rockfalls are rudimentary, relying only on eyewitness accounts and after-the-fact observations of fresh talus piles, which means many events are likely going unreported. In a new study, however, researchers interested in whether there’s a better way to monitor these events propose that seismic and infrasound sensors can help keep tabs on the granite slabs dropping from Yosemite’s cliffs.